Improvement of laser damage resistance and diffraction efficiency of multilayer dielectric diffraction gratings by HF etchback linewidth tailoring

Rapid growth processing of KDP crystals was improved by employing continuous filtration to eliminate bulk defects. The performances of the KDP crystals, including scattering defects, laser damage resistance and transmittance, were measured and analyzed. Compared with rapid-grown KDP without continuous filtration, the transmittance in the near-infrared was increased by at least 2%, almost all of ‘micron size’ defects were eliminated and ‘sub-micron size’ defects were decreased by approximately 90%. Laser damage testing revealed that the laser-induced damage thresholds (LIDTs), as well as the consistency of the LIDTs from sample to sample, were improved greatly. Moreover, it identified that ‘micron size’ defects were the precursors which initiated laser damage at relative lower laser fluence (4–6 J cm−2), and there was a lower correlation between smaller size scattering defects and laser damage initiation. The improved consistency in the LIDTs, attributed to elimination of ‘micron size’ defects, and LIDT enhancement originated from the decreased absorption of the KDP crystals.

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Relation of optical properties and femtosecond laser damage resistance for Al2O3/AlF3 and Al2O3/SiO2 composite coatings

Applied Optics ◽

10.1364/ao.53.00a383 ◽

2014 ◽

Vol 53 (4) ◽

pp. A383 ◽

Cited By ~ 11

Author(s):

Mathias Mende ◽

Istvan Balasa ◽

Henrik Ehlers ◽

Detlev Ristau ◽

Dam-be Douti ◽

...

Keyword(s):

Optical Properties ◽

Femtosecond Laser ◽

Composite Coatings ◽

Laser Damage ◽

Damage Resistance

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Synthesis of highly efficient multilayer dielectric diffraction gratings for spectral combining of laser beams

Numerical Methods and Programming (Vychislitel'nye Metody i Programmirovanie) ◽

10.26089/nummet.v22r312 ◽

2021 ◽

pp. 200-209

Author(s):

А.А. Петухов

Keyword(s):

High Efficiency ◽

Diffraction Order ◽

Diffraction Gratings ◽

Merit Function ◽

Synthesis Problem ◽

Laser Beams ◽

Etch Depth ◽

Technological Constraints ◽

Scattering Matrix Method ◽

Multilayer Dielectric

Статья посвящена синтезу многослойных диэлектрических отражательных дифракционных решеток, с высокой эффективностью обеспечивающих спектральное сложение пучков с различной длиной волны в заданном дифракционном порядке. Приводятся результаты решения задачи синтеза многослойных диэлектрических дифракционных решеток, обеспечивающих спектральное сложение в первом или минус первом порядке дифракции. Кроме того, решается задача синтеза для таких решеток с учетом возможных технологических ограничений на высоту профиля (глубину травления). Решение задачи синтеза проводится путем минимизации зависящего от параметров решетки целевого функционала методом Нелдера-Мида. Решение прямой задачи на каждом шаге минимизации осуществляется при помощи комбинации неполного метода Галеркина и метода матриц рассеяния. The paper is devoted to the synthesis of multilayer dielectric reflection diffraction gratings providing high-efficiency spectral combining of the beams with different wavelengths in a given diffraction order. The results are presented for solving the synthesis problems for multilayer dielectric diffraction gratings providing spectral combining in the first or minus first diffraction order. Besides, the synthesis problem for such gratings is solved with account taken of possible technological constraints imposed by the height of the grating profile (etch depth). The solution of the synthesis problem is obtained by means of Nelder-Mead minimization of the merit function depending on the grating parameters. At each minimization step the direct problem is solved using a combination of the incomplete Galerkin method and scattering matrix method.

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